Method for retrieval of a medical device

ABSTRACT

Funnel-trap type devices are described that are made of shape-set (e.g., heatset) braid for delivery and/or retrieval of Inferior Vena Cava (IVC) filters or other medical devices. Delivery and/or retrieval devices, kits in which they are included, methods of use and methods of manufacture are all contemplated. Additional forming tooling, methods and device embodiment shapes are described herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/569,500, filed Dec. 12, 2014, which is a continuation-in-part ofInternational Patent Application PCT/US2014/042343, filed Jun. 13, 2014,which claims priority to U.S. Provisional Application No. 61/835,295,filed Jun. 14, 2013, all of which are incorporated by reference hereinin their entireties and for all purposes.

FIELD

The embodiments described herein relate to endovascular (percutaneouslydelivered) Inferior Vena Cava (IVC) filter or other implants, retrievaldevices or system and methods.

BACKGROUND

Temporary IVC filters are placed much like permanent filters, but aredesigned so that they may be retrieved in a separate endovascularprocedure, generally from a femoral vein or internal jugular veinapproach. Most of the currently available temporary filters include ahook-like feature with which they can be captured and received within acatheter or sheath for removal by employing a gooseneck snare or amulti-loop snare.

While retrieval is a simple procedure in principle, difficulty is oftenencountered capturing a filter's hook with the snare loop(s). Suchdifficulty is compounded when the filter is tilted or off-kilter inplacement. Several filters are designed to avoid such orientation.However, the problem remains common because the device is not anchoredinto the IVC in a stable fashion. Constant blood flow in addition toblood clots can disorient the filter within the IVC making recapturedifficult.

Accordingly, there exists a need for a filter retrieval system withimproved ease of use and/or less susceptibility to problems of filterorientation.

SUMMARY

The example embodiments provided herein meet this need and others asapplied to other medical device applications. For IVC filters, thesubject systems may be used with a wide variety of filterarchitectures—existing or otherwise. Accordingly, new filters may bedesigned for use with the subject retrievers in which fewer designconstraints and/or compromises may be required of the filter design.Features of the subject system may be used in connection with existingand/or modified versions of the filters described in any of U.S. Pat.Nos. 3,952,747; 5,601,595; 6,443,972; 7,338,512 and 7,625,390 (all ofwhich patents are incorporated herein by reference in their entiretiesfor any purpose), commercially available devices including the OPTEASE,GUNTHER TULIP, CELECT and OPTION or others.

Example embodiments of the subject delivery and/or retrieval devices,kits in which they are included (with and without assembly), methods ofuse and manufacture (including assembly of the constituent components invivo or ex vivo) are all included within the scope of the presentdisclosure.

Other systems, devices, methods, features and advantages of the subjectmatter described herein will be or will become apparent to one withskill in the art upon examination of the following figures and detaileddescription. It is intended that all such additional systems, devices,methods, features and advantages be included within this description, bewithin the scope of the subject matter described herein, and beprotected by the accompanying claims. In no way should the features ofthe example embodiments be construed as limiting the appended claims,absent express recitation of those features in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the subject matter set forth herein, both as to itsstructure and operation, may be apparent by study of the accompanyingfigures, in which like reference numerals refer to like parts. Thecomponents in the figures are not necessarily to scale, emphasis insteadbeing placed upon illustrating the principles of the subject matter.Moreover, all illustrations are intended to convey concepts, whererelative sizes, shapes and other detailed attributes may be illustratedschematically rather than literally or precisely.

FIGS. 1A and 1B are photographs depicting example embodiments of IVCfilters.

FIGS. 2A-2E are side views depicting an example embodiment of a deliveryand/or retrieval system in various stages of action in connection withan end of any type of implantable medical device (IVC filter orotherwise).

FIGS. 3A-3F are side and cross-sectional views depicting exampleembodiments of components used in the manufacture of a preform forconstructing the subject retrieval system.

FIG. 4A is a partial cross-sectional view depicting an exampleembodiment of tooling for converting the preform to a finally-shapedmedical device; FIG. 4B is a partial cross-sectional view depicting anexample embodiment of the tooling of FIG. 4A in use to shape an exampleembodiment of the medical device.

FIG. 5A is a partial cross-sectional view depicting another exampleembodiment of tooling for converting the preform to a finally-shapedmedical device; FIG. 5B is a partial cross-sectional view depicting anexample embodiment of the tooling of FIG. 5A in use to shape an exampleembodiment of the medical device.

FIG. 6 is a cross-sectional view depicting an example embodiment of aconverted preform (i.e., a finally shaped funnel section of the subjectdevice) after heatsetting.

FIG. 7A is a partial cross-sectional view depicting another exampleembodiment of tooling for converting the preform to a finally-shapedmedical device; FIG. 7B is a partial cross-sectional view depicting anexample embodiment of the tooling of FIG. 7A in use to shape an exampleembodiment of the medical device.

FIG. 8 is a partial cross-sectional view depicting an example embodimentof a medical device after its preform is heatset with tooling like thatof FIGS. 7A and 7B.

FIG. 9 is a cross-sectional view depicting an example embodiment of apreform set in a different shape using the tooling like that of FIGS. 7Aand 7B.

FIG. 10 is a partial cross-sectional view depicting an exampleembodiment of an additional tool piece that may be used in conjunctionwith tooling like that of FIGS. 7A and 7B.

FIG. 11 is a cross-sectional view depicting an example embodiment of apreform that may be heatset using the tool piece of FIG. 10.

FIGS. 12A-12C are top, side, and front views, respectively, of anexample embodiment of another tool piece that may be used in conjunctionwith tooling like that shown in FIGS. 7A and 7B.

FIG. 13 is a cross-sectional view depicting an example embodiment of apreform that may be heatset with tooling like that of FIGS. 12A-12C.

DETAILED DESCRIPTION

Before the present subject matter is described in detail, it is to beunderstood that this disclosure is not limited to the particular exampleembodiments described, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present disclosure will be limited onlyby the appended claims.

All features, elements, components, functions, and steps described withrespect to any embodiment provided herein are intended to be freelycombinable and substitutable with those from any other embodiment. If acertain feature, element, component, function, or step is described withrespect to only one embodiment, then it should be understood that thatfeature, element, component, function, or step can be used with everyother embodiment described herein unless explicitly stated otherwise.This paragraph therefore serves as antecedent basis and written supportfor the introduction of claims, at any time, that combine features,elements, components, functions, and steps from different embodiments,or that substitute features, elements, components, functions, and stepsfrom one embodiment with those of another, even if the followingdescription does not explicitly state, in a particular instance, thatsuch combinations or substitutions are possible. Express recitation ofevery possible combination and substitution is overly burdensome,especially given that the permissibility of each and every suchcombination and substitution will be readily recognized by those ofordinary skill in the art upon reading this description.

FIG. 1A shows a GUNTHER TULIP (Cook Medical, Inc.) temporary IVC filter10 with a hook 12 end interface for retrieval. As shown in FIG. 1B foran IVC filter 20, the hook may be modified or substituted for anubbin-type interface 22. The nubbin (itself) may comprise alaser-formed or solder-formed protuberance or bump 24 on an extension 26from a hub 28. Alternatively, as shown in FIGS. 2A-2E, the filterretrieval interface 22 may comprise a band 24′ (e.g., a Pt marker band)mounted (e.g., by swaging, welding, gluing, etc.) on the extension 26.However, the enlargement is created, its interaction with the rest ofthe system will be apparent in the following figures.

Accordingly, FIG. 2A provides an overview of an example embodiment ofthe system 100. Here, a funnel-trap structure 30 made of braid material32 is shown. It provides a flexible distal extension to an elongateshaft 34. The shaft is received within an elongate sleeve 50 (that maybe a commercially available catheter or a custom part of the overallsystem 100) and may include a distal radiopaque marker band 52.

The braid may comprise Nitinol (preferably that is superelastic at bodytemperature), CoCr, Stainless Steel or another biocompatible material.It is advantageously braided material incorporating between 72 and 288(more typically between 96 or 144 and 192) filament “ends” in a1-over-1, a 2-over-2 or other maypole braided pattern. The braid mayinclude so-called “axial” filaments as well. These may be used toimprove column strength in a finally-formed device. The axial filamentsmay be incorporated in a/the maypole braided pattern when it is beingformed or be added later manually. With (superelastic) Nitinol, the wireis advantageously between about 0.001 and about 0.003 inches indiameter. In which case, a supple and relatively “smooth” matrix surfaceis provided from which to construct the flexible funnel-traparchitecture shown and described. The value of such a surface is in itsatraumatic aspect and/or ability to help guide in IVC filter interfaceinto position for capture even if it is oriented off-angle. Still, otherwire size and/or end count in a braid or other construction options arepossible as well. In alternative embodiments, non-braided materials areused.

To further assist with recapture, the funnel trap structure 30 may beselectably directable. As indicated by the arrows in FIG. 2A, thematerial from which it is made can be heatset or otherwise configured toprovide a bias in an angular direction. The angle of deployment may beselectable or fully straightened by relative position of a core memberor obturator (not shown) or by a sleeve or catheter sheath as furtherdescribed. Further positioning may be achieved by rotating the device asfurther illustrated.

Other device articulation options for selecting the angular orientationof the subject funnel-trap portion of the device are possible as well.Any of a variety of steerable or directable catheter-type technologies(reliant on pull-wires or otherwise) can be incorporated in shaft 34 forsuch purposes. Examples include the mechanisms described in U.S. Pat.Nos. 4,723,936; 4,960,411; 6,251,092 and 8,273,073 each incorporatedherein by reference in its entirety for such description.

In any case, FIG. 2B shows an advantageous construction of a braidedmulti-filar device in cross section. Here, inner and outer braid layers32/32′ are heatset using conventional techniques (e.g., in a furnace,salt pot, etc.) in a funnel shape with distal bends 36 in the braid wireforming an outer rim 40 with a large(r) distal opening and a meeting atinner bends 38 forming an inner rim 42 with a small(er) more proximalopening. Stated otherwise, the braid used to construct the funnel-shapetrap is folded back (e.g., in a flap 46) at the distal opening toprovide a more proximal opening.

This “funnel trap” may be generally frusto-conical as shown, tapered,flared or otherwise configured with a distal opening that is relativelylarger than the proximal opening within the distal retrieval section.With an outer conical shape (i.e., triangular shape in cross section)the structure is highly supportive for any necessary or desirable tissuediscretion that might need to occur to free an emplaced filter.Moreover, such a shape provides a flexible “waist” section 48 for thedirectable feature(s) noted above. Still, the device may be bowedoutward along its sides or otherwise configured in alternativeembodiments.

In many embodiments the distal rim opening 40 is larger than the moreproximal rim opening 42 to operate as illustrated in guiding filterengagement feature(s) or enlargement 24/24′ into a pocket 44 where it iscaptured and subsequently locked upon advancing sleeve 50 as shown inFIGS. 2D and 2E.

As shown, such a pocket 44 is formed between braid 32 walls and bend 38ends optionally serving as an abutment feature with an optional shoulder38′ of nubbin/bump 24/24′. To ensure capture, the sleeve 50 may beadvanced fully over trap 30 as shown in FIG. 2E before withdrawal into aseparate catheter. In other words, advancing sleeve 50 over funnelsection 30 “closes the trap” and securely captures the implant to beretrieved. Otherwise, the sleeve may be a catheter and shaft 34 withdrawcontinue until the implant (at left) is pulled therein as well. Any orall such activity may be visualized fluoroscopically by a physician byway of marker features 24/24′ and 52 and/or others as may beconveniently provided. In alternative embodiments, the folded sectioncan be omitted so long as the distal opening remains larger than theproximal opening and the trap functionality is retained.

Notably, system 100 may be used identically when capturing a filter 10with a more typical hook end 12. However, the additional bulk/lateralextension of the hook may necessitate use of a relatively larger sleeveor catheter 50 than pictured in FIGS. 2A-2E.

In the various system architecture embodiments, the catheter/pushershaft and/or sleeve may comprise a simple extrusion (e.g., PTFE, FEP,PEEK, PI, etc.) or may be constructed using conventional catheterconstruction techniques and include a liner, braid support and outerjacket (not shown), metal hypotube, etc. Further, the filter frame maybe constructed using conventional laser cutting and electropolishingtechniques and/or be otherwise constructed. In embodiments intended fortracking through a guide/delivery catheter without an incorporatedsheath, a loading sheath may be employed. Advantageously, any suchloading sheath is splittable. Other typical percutaneous accessinstruments (such as wires, etc.), valves and other hardware may also beemployed in the embodiments.

The funnel-trap structure 30 may be made as a subassembly and attachedto the catheter/pusher shaft. FIGS. 3A-3F detail optional steps in themanufacture of a pre-form for constructing the funnel-trap portion ofthe final device.

In FIG. 3A, a length or section 200 of braid as described above isprovided. As shown, the braid pattern of crossing filaments may includeinterwoven angled elements as well as interwoven axial elements. Theaxial elements may comprise the same size and/or type of material (e.g.,Nitinol) or more radiopaque material such at Pt, CoCr or StainlessSteel. As few as four axial members may be incorporated in the braid.More often six, eight or more such filaments are included. When axialfilaments are employed which are smaller in diameter that the interwovenangular fibers, their number used may be greater. When relatively largeraxial fibers are employed, the number used may be fewer. Regardless, thebraid is advantageously heatset under tension upon the mandrel on whichit was formed. As described by now-expired U.S. Pat. No. 6,447,531, suchan approach enhances braid stability for subsequent device formation infurther shape-setting of the device.

In FIG. 3B (a cross-section view), the braid section is shown doubledover a section hypotube 300. This may be accomplished by everting whatis now an outer layer 202 of the braid 200 over the hypotube afterfeeding the inner layer 204 of braid there through. Alternatively, theinner layer may be fed into and through the hypotube after the outerlayer is set over the hypotube. In any case, the braid wires are bent ina fold 210 at a distal end of the hypotube. Next, the braid is securedto the hypotube for heatsetting (e.g., at 520.degree. C. for 5 minutesfor Nitinol braid). The braid may be secured by winding or wrapping withmalleable wire or external forms (not shown) may be used to hold thebraid relative to the hypotube for heatsetting. A press-fit rod or plug301 may be used to secure and/or further compress the fold 210.

After heatsetting, the hypotube is removed as shown in FIG. 3C leavingonly braid 200 in layers 202 and 204. As shown in FIG. 3D, the braidlayers may be trimmed (e.g., with scissors) to the same length. In FIG.3D (another cross-section view), a band 302 is inserted to abut the foldin the braid.

As with hypotube 300, band 302 preferably comprises strong material ofminimal thickness. In each case, the structure is associated withforming bends in the braided wire. Thinner material will yield a tighterradius fold of the braid (or bend in the braid wires) as described.Advantageously, each of hypotube 300 and band 302 comprise superelasticNitinol given that in the desired wall thickness (i.e., from about 0.001to about 0.002 inches) such parts are tough and less prone todeformation and/or tearing as similarly-configured (otherwise usable)stainless steel, platinum or brass pieces.

Once prepared with band 302, the folded braid and band can be receivedwithin a pocket or socket 312 of a rod 310 or an end of another tube orhypotube. The pocket may offer a light press fit to the braid.Otherwise, the band-and-braid intermediate construction may be securedin socket 310 with glue (e.g., LOCTITE 4014).

Then, both layers of braid 202/204 are flipped or everted over the rodand secured thereto (e.g., as by wrapping per above) as shown in FIG.3E. So-fixtured, braid 200 includes a second fold 212 as shown in(cross-section view) FIG. 3E. Upon heatsetting (e.g., again, as perabove), the fold(s) are set or fixed in shape. Then, the rod and bandare removed providing a finished preform 220 as shown in FIG. 3F.

Such an approach to forming the bends 210/212 is advantageous in view ofits simplified tooling. Further, the tooling used (i.e., bands and/ortubes) for this approach can be minimized in thickness to provide thetightest folds possible in the braid. As such, minimum diameter can beachieved for the compressed medical device as ultimately formed.

Regarding such formation (i.e., conversion from preform to final deviceconfiguration), FIG. 4A illustrates an example embodiment of a first setof tooling 320 that may be so-used. Toolset 320 includes an internalform or mandrel 330 and an external form 340 with cavity 342. These areshown in use relative to preform 220 in (cross-section view) FIG. 4B.With the braid so-positioned and secured over a rod 322 (e.g., tied-downas per above), optionally in connection with a setscrew 324, the braidis heated within the tooling construct to define a final funnel-trapdevice shape (e.g., as elaborated upon in connection with FIG. 6).

Notably, this final heatsetting cycle may take longer than previouscycles due to the thermal mass of the tooling. As such, it may bedesirable to heat treat for approximately 10 minutes at temperature.Furthermore, it may be desirable to heatset in an inert atmosphere tominimize oxide formation. The same holds true for preceding heatsettingactivities.

As for specific tooling features, mandrel 330 includes cone sections332/332′ and shoulder sections 334/334′. Together, these sectionsprovide guidance for final device angular configuration and formation. Arod clearance hold 336 and a threaded setscrew hole 338 may also beprovided in mandrel 330. External form 340 includes the aforementionedpocket 342 as well as optional setscrew and rod clearance holes 344 and346, respectively.

External form 340 need not be used in shape-setting. However, itsuse/inclusion in the forming process may advantageously reducepart-to-part variability by further constraint in its application.

FIG. 5A illustrates an example embodiment of a second tooling approachfor converting the preform 220 to a finally shaped device. Here, atwo-part mandrel 350 is provided. It includes a cone piece 360 with anangled inset or pocket 362 that offers potential advantages byconstraining the flap and fold 212 of the braid at rim or lip 364. Anabutment piece 370 of tool 350 may be used to further constrain thebraid. It includes a cone section 372 complementary to inset 362 and mayalso include a shoulder section 374 to further constrain or compress thebraid during heatsetting. Together (or using cone piece 360, alone) theadditional constraint in the fold and flap region—as compared to theconfiguration offered with mandrel 330—may obviate the need or advantageof using an external form like form 340 in the forming process such asshown in (cross-section view) FIG. 5B. Still, an external form (likeform 340 shown in FIG. 4A) may be used in connection with tooling 350.

In general, the aforementioned forming methods are ones in which aheatset (possibly multiple-staged heatset) preform is provided that issubstantially cylindrical in shape and includes an interior folded“flap” section. As such, the preform resembles the subject device in itsfully compressed state for catheter tracking. Then, the preform isexpanded (e.g., in a conical shape) to a desired “working” configurationand heatset accordingly.

Another forming and tooling approach may use thin-wall conical bands(not shown) in the shape-setting procedure. These may be used todirectly shape or form the cone and flap sections of trap device 30.Such tooling may be constructed by “spinning” down thin-walledcylindrical material to the desired conical shapes and then trimmingfinal pieces to length. However, use of internal tooling (as such) maylimit the extent to which the braid layers lay in apposition afterheatsetting, thereby resulting is some gap between the layers (i.e.,unless the braid is subsequently formed with tooling as shown in FIGS.4A/5A or otherwise).

Regardless of which tooling approach is employed, FIG. 6 illustrates apreform after conversion (or braid otherwise formed) to the subjectfunnel-trap device portion 30. For IVC filter retrieval, the funnel-trapportion 30 may have a diameter (D) from about 5 mm to about 20 mm, ormore preferably about 10 to about 15 mm (i.e., size in a range to workwithin average size human IVCs where such vessels are reported as havinga mean diameter of 20 mm within a range of 13 to 30 mm). A length (L)may range from about 10 mm to about 30 mm. An overall cone angle (α) maybe between about 30 and about 90 degrees. An angle (β) of flap 46 may bebetween about 0 and about 60 degrees and flap length (F) may be betweenabout 1 and about 10 mm in length. Overall, a funnel trap openingdiameter (d) may be between about 5 and about 95 percent of diameter (D)depending on the selected combination of the noted variables (i.e., d,D, L, F, α and (β). At the lower end of this range, the inner “opening”may be substantially closed such that is must be pushed-open to receivethe proximal engagement feature(s) of the implant during retrieval. Atthe higher end of the range, the flap may lie completely along orin-line with the outer layer(s) of the device.

FIG. 7A illustrates another example embodiment for converting the shapeof a preform. Namely, tooling 400 is used to produce a second orsecondary preform shape 500 as shown in FIG. 8 and further describedbelow.

The tooling or toolset 400 includes a cylindrical shell or tube 402. Aplug 410 is provided for its proximal end 402. A distal end 406 of thetube may be cut at 90 degrees or at an angle (see dashed profile)relative to an axis (not shown). Alternatively, an undulating orsaddle-shaped profile may be substituted therefore as indicated.

In any case, the end may be formed as a sharpened edge 408 (e.g., usinga counter bore, de-burring tool or otherwise). Plug 410 includes innerand outer cylinder sections 412, 414. Inner section 412 is sized to fitwithin tube 402 with a shoulder 416 of the plug abutting the tube. Plug410 also includes a through hole 418 to accommodate wire 420. Wire 420may also pass through a band 422 through apertures 424.

Such an arrangement is shown in FIG. 7B. Specifically, wire 420 islooped and passes through apertures 424 in band 422 and proximallythrough plug 410. At or near a proximal end of the wire, a boss 430 witha set screw 432 secures the wire under tension applied by a spring 434.A coil spring is shown, although various leaf spring or spring washerarrangements may alternatively be used.

In any case, spring tension is held at the opposite end of the wire bythe braid 200 in which band 422 is captured. The braid is folded overtube 402 to form its distal bend 36 and secured to the tube with a wirewrap 440 or other clamping mechanism. In setting up the distance betweenthe proximal side of band 422 (together with associated flap 46) asizing tube 442 may be temporarily interposed as shown and removed priorto inserting plug 430 into tube 402 and tensioning wire 420 and braid200.

Once heatset, the product (i.e., the second or secondary shape preform500) appears with a cylindrical outer body 502 and an angled interiorflap 46 as indicated in FIG. 8. Once a heat shrink sheath 504 or otherconstraint is applied thereto, the device takes its final shape and isready for mounting on a catheter or pusher body as the funnel trapportion of the overall device.

The shaping sheath 504 may be permanently included in the finalconstruction (i.e., form part of the product's catheter shaft or pusher)or it may be temporarily used in a heatsetting procedure to finallyshape the device. Alternatively, a wire wrap (not shown) may be used toeffect an additional heatsetting cycle to finalize the shape.

The ultimate cross-sectional profile may appear as it does in FIG. 8with a face or opening 40 set at 90 degrees relative to an axis definedby the body of the device. Alternatively, the opening may be as shown infunnel trap portion 510 in FIG. 9 where it is angled relative to such anaxis 512 of the body by an acute angle y. In which case, the angle mayadvantageously range from about 45 to about 60 degrees.

A face or opening 40 so-angled provides a leading edge 514 forpicking-up IVC filter hooks and/or nubs adjacent the vessel wall. Theshape may help when rotating the body of the retrieval device into sucha target structure or anatomy, or be otherwise employed. Moreover, thevarious directional or directable aspects of the system(s) describedabove may be so-employed.

In forming a device portion or preform with an angled distal end (e.g.,as shown in FIG. 9), the proximal aperture or opening 516 may be set atand offset distance “0” in order to take-up slack that would otherwisebe present in the braid when heatsetting the angled shape. Removing theslack in the braid (as such) enables uniform tensioning of the braid informing a tight distal crease or fold around over angled tooling edge408 (e.g., as in tooling 400 shown in FIGS. 7A and 7B).

FIG. 10 illustrates an example embodiment of another heat setting formor tool piece 450 that may be used in conjunction with tooling 400. Byits use, a funnel trap section 520 can be formed as shown in FIG. 11.The complimentary nature of the shapes illustrated is apparent.

More specifically, a/the proximal aperture or opening 522 is centered.To allow for this, a shoulder or arch portion 452 of tool 450 is used todeform and tighten the braid of the funnel trap over a complimentary arc524 along its down-angle side. Tool 450 is simply used in line with wire420, band 422, boss 430 and the other tooling shown in FIG. 7B to createsuch a heatset in the braid.

FIG. 12A-12C shows views of an example embodiment of another tool piece460 used for braid tensioning to account for shell 402 edge asymmetry. Apreform conversion or final funnel trap section 530 with a tight distalfold or crease around a “fishmouth” or “saddle” shape distal opening orend 532 can be produced in connection with such a tool piece or form. Inwhich case, shell 402 is configured with the saddle-shaped profile shownin FIG. 7A.

So-formed, funnel trap section 530 includes two protruding curved lips,edges or ridges 534 (as compared to having one leading edge or ridge 514as in the variations shown in FIGS. 9 and 11). Such a shape may beadvantageous in reducing procedural complexity and any necessaryrotation in securing the end of a filter.

Forming such a complex shape can be challenging. Yet, tool piece 460with its biased shape (i.e., tapered from an oval or elliptical base 462to a circular cross-section end or tip 464) enables a taught fit of thebraid from which the device is made over the saddle-shaped edge of shell402. As such, a tightly creased rim or edge can be effectively heatsetin the braid at the distal end of the device.

In each example of a device section 520 and 530, the braid is formedwith a tool (450, 460) in the form of a plug that asymmetricallytensions or loads the braid. The asymmetry in the plug and/or the braidtensioning enables centering the proximal aperture of the funnel trapdevice for IVC filter hook or nub capture. Other uses of the techniquemay be possible as well.

All of the embodiments described herein are freely interchangeable. Forexample, all of the example embodiments of filters can be used with allof the embodiments of the delivery or retrieval devices and all of theexample embodiments of the delivery or retrieval devices can bemanufactured with all of the example embodiments of manufacturingtooling and manufacturing steps as described or with minor modificationsthat would be evident to those of ordinary skill in the art upon reviewof this disclosure.

Variations

The subject methods, including methods of use and/or manufacture, may becarried out in any order of the events which is logically possible, aswell as any recited order of events. Medical methods may include any ofa hospital staff's activities associated with device provision, implantpositioning, re-positioning, retrieval and/or release.

Furthermore, where a range of values is provided, it is understood thatevery intervening value, between the upper and lower limit of that rangeand any other stated or intervening value in the stated range isencompassed within the disclosure. Also, it is contemplated that anyoptional feature of the embodiments described may be set forth andclaimed independently, or in combination with any one or more of thefeatures described herein.

Reference to a singular item includes the possibility that there are aplurality of the same items present. More specifically, as used hereinand in the appended claims, the singular forms “a,” “an,” “said,” and“the” include plural referents unless specifically stated otherwise. Inother words, use of the articles allow for “at least one” of the subjectitem in the description above as well as the claims below. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation.

Without the use of such exclusive terminology, the term “comprising” inthe claims shall allow for the inclusion of any additionalelement—irrespective of whether a given number of elements areenumerated in the claim, or the addition of a feature could be regardedas transforming the nature of an element set forth in the claims. Exceptas specifically defined herein, all technical and scientific terms usedherein are to be given as broad a commonly understood meaning aspossible while maintaining claim validity. Accordingly, the breadth ofthe different embodiments or aspects described herein is not to belimited to the examples provided and/or the subject specification, butrather only by the scope of the issued claim language.

The invention claimed is:
 1. A method for delivery or retrieval of amedical device, the method comprising: passing an elongate shaft havinga longitudinal axis through a body lumen of a subject, the shaft havinga flexible distal extension folded back at a first fold to form twolayers, the two layers folded back inwardly at a second fold such thatthe first fold is a proximal opening of a funnel and the second fold isa distal opening of the funnel, wherein the distal opening is configuredto have a saddle shape cross section and to be set at an acute anglerelative to the axis of the shaft upon deployment; and passing an endportion of the medical device through the distal opening and thenthrough the proximal opening of the funnel to capture the medicaldevice.
 2. The method of claim 1, wherein the distal extension comprisesheatset Nitinol braid with between 72 and 288 end count.
 3. The methodof claim 2, wherein the shaft includes the Nitinol braid.
 4. The methodof claim 1, wherein the distal extension has an exterior conical shape.5. The method of claim 1, wherein the acute angle is between about 45and about 60 degrees.
 6. The method of claim 1, further comprisingcovering the medical device with an elongate sleeve.
 7. The method ofclaim 6, wherein the elongate sleeve is a catheter.
 8. The method ofclaim 6, wherein the distal opening is configured to close and trap theend portion of the medical device within the distal extension whencovered by the elongate sleeve.
 9. The method of claim 8, wherein theproximal opening is configured to close and trap the end portion of themedical device within the distal extension when covered by the elongatesleeve.
 10. The method of claim 6, wherein the elongate sleeve isadvanced to cover the medical device.
 11. The method of claim 10,wherein medical device is withdrawn through the elongate sleeve afterthe elongate sleeve is advanced.
 12. The method of claim 6, wherein aportion of the medical device is captured in a pocket of the distalextension by covering with the sleeve.
 13. The method of claim 1,wherein a portion of the proximal opening is at least partially closedto capture the medical device.
 14. The method of claim 13, wherein theproximal opening is at least partially closed by retracting a tether.15. The method of claim 1, wherein the medical device includes a hookand the hook is captured at the proximal aperture.
 16. The method ofclaim 15, wherein the hook engages at least one of a rim or an aperturecrossing member at the proximal opening for capture.
 17. The method ofclaim 1, wherein the proximal opening is sized to receive and pass anend portion of the medical device to situate and secure the end portionof the medical device within the flexible distal extension when thesleeve is advanced over the distal extension.